I know I’m pretty well known for long responses on these forums, but I’m kinda tired now, so I’ll try to stick to the basics even though I’m admittedly very flashcard-averse, so I can’t help with WK SRS specifics.
I’d slow down and focus on what I can’t seem to learn and ask myself how I can retain it better. Do you have any really strong memories? Is there anything they all share (association with strong emotions, vivid sensations etc)? Is there anything you’ve found helps you learn in general? If the answer to any of those questions is yes, then see if you can apply that fo learning Japanese. Do you have trouble with visualisation? If you can’t do it at all, don’t worry: there are lots of people like that on these forums too. It’s just that my memory is very visual and imaginative in the sensory department, so I don’t think my experience would help you directly. But you can still try to make things interesting or whacky for yourself so they stick better.
That aside, I think a lot of us (myself included) find that meaningfulness and context help a lot, so you might want to do a little Japanese on the side in some other form like anime, dramas and songs. It’s a lot easier to remember an epic moment in a story or a vocal performance than a word or sentence you know nothing about. I also know that some people don’t like WK’s context sentences, so if you feel like you need better ones, try searching on sites like Jisho and https://ejje.weblio.jp. (Yes, Japanese interface, but I promise you that you’ll see tons of translated examples the moment you use the search bar.) There’s also a ‘better context sentences’ userscript somewhere, I think. Try searching the forums.
I wish I had more potentially helpful ideas, but that’s all the general stuff I can think of for the moment. I’d give some visualisation- and etymology-specific advice, but because I don’t know if visualisation helps you, I don’t want to mention anything that might be useless for you. Either way, I wish you all the best, and welcome any questions.
